1. Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus using the same.
2. Description of the Related Art
In recent years, instead of a silver-salt film camera, a digital camera in which, an object is photographed by using an image pickup element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) has become a mainstream. Furthermore, there are several categories of digital cameras in a wide range from a high-function type for professional use to a compact popular and widely-used type.
From among the digital cameras in the wide range, with the popular and widely-used type digital camera, a user seeks to enjoy photography readily, anywhere at any time with a wide range of scenes. Particularly, since a slim digital camera can be accommodated easily in a pocket of clothes or a bag, and can be carried conveniently, such digital camera has been preferred. Due to this, further small-sizing even of a taking-lens system has been required.
Moreover, since the number of pixels of an image pickup element tends to increase, an improved optical performance corresponding to the increase in the number of pixels has been required. From a point of view of widening a capture area, a zoom lens having a zoom ratio of more than 10 times is becoming common, and even higher zoom ratio is required. On the other hand, an angle of view is also expected to increase.
In order that such requirements are fulfilled, various zoom lens systems have been proposed. As a zoom lens which is compact and having a high zoom ratio, a zoom lens which includes in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power has hitherto been known (Japanese Patent Application Laid-open Publication Nos. 2010-276655, 2011-33868, 2009-186983 and 2009-163066)